1. Field of the Invention
The present invention relates generally to seals for coaxial cable connectors, and particularly to seals for sealing gaps at interfaces between coaxial cable connectors and terminals.
2. Technical Background
Coaxial cable connectors such as F-connectors are used to attach a coaxial cable to another object such as an appliance or junction having a terminal adapted to engage the coaxial cable connector. When used outdoors in weather-exposed areas it is desirable to prevent moisture from entering the terminal/connector/cable system. Various connectors are commercially available for outdoor applications and generally prevent moisture from entering the connector/cable junction. Such connectors must be attached to a coaxial cable using various cable preparation techniques and installation tools. Cable preparation typically requires removal of portion of the cable jacket, braid, outer conductor and core to expose the cable center conductor. Another portion of the cable jacket is removed to expose the cable braid. Cable preparation is often completed by folding of the cable braid structure back against the remaining cable jacket. The cable is then inserted into the connector, after which the connector is activated to secure the connector to the coaxial cable. For outdoor applications the connector is generally sealed to the cable either by the internal workings of the connector or by the use of an external sealant, heat shrinkable tubing, rubber cement, fusing tape or rubberized boot.
In order to maintain the integrity of the coaxial system, moisture must be prevented from entering the connector/appliance junction as well. In the past, others have attempted to provide a connector/appliance seal by using a rubber type material in the form of a tight fitting ring with an inner bore and an outer diameter or shape. For various reasons, the foregoing attempts have yielded less than satisfactory results. For example, attempts at encapsulating the connectors with tapes, shrink wrappings and plastic or rubber cements are too prone to installation errors, resulting in exposed seams and/or internal voids where moisture can collect and eventually penetrate to the cable junction. Moreover, shrink wrappings require the use of heat or chemicals which further complicate installation procedures. Cements require time to set up and cure, thus also prolonging and complicating installation procedures. The use of sealing components such as externally applied flexible boots and/or grommets again results in internal voids where moisture can collect. Installation of tight fitting seal rings is difficult and therefore many times is avoided. Subsequent removal of tight fitting seal rings after a lengthy period of service can be even more difficult than installation and oftentimes requires the use of a knife or similar instrument to cut the seal ring off of the appliance junction. This can likely result in damage to the junction threads and is not desirable. Additionally, existing seal rings are limited in use by the length of terminal port on which they are installed. A specific length seal ring must be matched with and installed on a terminal port of compatible length, thereby requiring the technician to recognize various port lengths and have a correct assortment of seal rings on hand. One example of a known seal ring is illustrated in FIG. 1. As illustrated, a seal ring 10 typically has a smooth outer surface 12 and a first internal bore 14 that is slightly smaller than the diameter of the threaded section 16 of terminal 18. Terminal 18 projects out from a wall surface, for example the exterior surface of an electrical or electronic device. This seal ring 10 also has a second internal bore 20 that has a diameter slightly smaller than the coupling nut 22 associated with coaxial cable connector 24. In this manner, a tight seal may be achieved by the tight fit between the seal ring 10 and, at each end, the coupling nut 22 and the threaded section 16 of terminal 18.
However, this and many of the known seal rings cover substantially most of the threads on the appliance port and require that at least a portion of the corresponding cable connector coupler engage the seal ring while engaging the port threads. This engagement of the seal ring can cause difficulty in turning the connector coupler, making the connector hard to install.